1. Field
This invention relates to a keyboard switch assembly and more particularly, to a key actuated multiple switch assembly.
2. Description of the Prior Art
Prior art mechanical keyboards used in typewriters have employed keys which, when depressed with a first force level, effect print actuation and which when depressed with a greater force over a further distance, effect repeated printing. Recently, electronic keyboard advancements have made these units more reliable and less costly than prior mechanical keyboards. However, it is desirous for the electronic keyboards to have the same tactile response to an operator and function in the same manner as the prior mechanical keyboards since most operators are trained on and are familiar with the prior mechanical keyboards.
It has been found that capacitively coupled electronic keyboards provide cost savings and reliable operation when compared to other electronic keyboards including those employing contact or ohmic switching elements. However, prior art approaches to provide an economical second switch to effect a repeated printing function in conjunction with a capacitive switch used to effect character selection and printing have resulted in unreliable devices or in devices which do not provide the same tactile response and which do not function in the same manner as prior mechanical keyboards which are familiar to typists. Examples of such approaches are described in the IBM Technical Disclosure Bulletin (TDB) of June, 1974 at page 164. They involve having the operator hold the key beyond a time out period to effect repeated key entry or the adding of an extra switch mechanism. The extra switch mechanism disclosed in the TDB article comprises a shorting clip located under certain keybuttons which is made to contact a printed circuit board when the key is fully depressed with a second force level. Although this device tactilely behaves like the prior mechanical keyboards, it is not reliable since the switch contacts are subject to bending, misorientation and/or contamination failure.